The fabrication of semiconductor components, for example semiconductor wafers, dies and integrated circuit (IC) chips, typically involves numerous processing steps. Such processing steps typically include, but are not limited to, visual inspection and electrical testing of the semiconductor components.
Each processing step typically occurs at a different and distinct processing station and by a different processing module. There currently exist several systems and apparatuses for transferring the semiconductor components between processing stations. Typically, the semiconductor component is first picked up or received by the system or apparatus at a first position (or an input position) and transferred between the different processing stations before being thereafter deposited or detached at a second position (or output position). The semiconductor components are processed at the processing stations either while in motion or when temporarily stationary at the processing stations depending on the processing requirements.
Several existing or conventional systems or apparatuses for transferring semiconductor components comprise a rotatable turret having multiple pick-up heads (also known as semiconductor component handlers). The pickup heads are operable for receiving, holding, and transferring the semiconductor components. Rotation of the turret displaces the pick-up heads along a predetermined travel profile. Generally, the semiconductor components received and held by the pickup heads are transferred to be positioned at the different processing stations for processing at the processing stations as the pick-up heads are displaced along the predetermined travel profile.
Each pick-up head or semiconductor handler comprises means or a mechanism for picking up or receiving the semiconductor component at the first position, as well as means or a mechanism for depositing or detaching the semiconductor component at the second position. In addition, each pick-up head comprises means or a mechanism for securing or holding the semiconductor component thereto during displacement along the predetermined travel profile.
A first exemplary existing turret structure 200, as partially shown in FIG. 1a and FIG. 1b, comprises a central shaft 202 and a rotatable portion 204 coupled to the central shaft 202. The rotatable portion 204 typically comprises at least one pick-up head 208, which picks up semiconductor components at a first position, rotates around the central shaft 202 for transferring the semiconductor components attached thereto, and deposits the semiconductor component at a second position. The central shaft 202 comprises a number of air tubes, each having a fixed spatial position. Vacuum is applied via a first air tube 206, and through a pick-up head 208, for picking up the semiconductor component at the first position. The pick-up head 208 then rotates around the central shaft 202 to the second position. At the second position, air is purged through a second air tube 210, and thereafter through the pick-up head 208 for detaching the semiconductor component from the pick-up head 208. As shown in FIG. 1a, the pick-up head 208 is directly connected to the first air tube 206, and vacuum pressure is stable therebetween. The same is the case as shown in FIG. 1b where the vacuum pressure is stable between the pick-up head 208 and the second air tube 210. When the pick-up head 208 is displaced from the first position to the second position, no vacuum pressure is applied thereto. This absence of applied vacuum pressure often results in dislodging of the semiconductor component from the pick-up head 208. A problem with this first exemplary existing turret structure 200 is a possibility of an insufficient vacuum for adequately securing the semiconductor component to the pick-up head 208 during rotation of the pick-up head 208 around the central shaft 202 from the first position to the second position. Accordingly, this may result in unwanted dislodging of the semiconductor components from the pick-up head 208 during the rotation of the pick-up head 208 from the first position to the second position. In order to prevent the unwanted dislodgement of the semiconductor components from the pick-up heads 208, the rotation of the pick-up heads 208 has to occur at a relatively high speed. However, centripetal force exerted on the semiconductor component attached to the pick up head 208 generally increases with the increasing speed of rotation of the pick-up head 208. Accordingly, a fine balance or optimization between applied vacuum and speed of rotation needs to be achieved for securing the semiconductor components to the pick-up head 208 of the first exemplary existing turret structure 200. This fine balance or optimization is generally difficult to achieve, especially with the increased need for speed during transfer of semiconductor components.
A second exemplary turret structure 250, as shown in FIG. 2, comprises a central shaft 252, a rotatable portion 254 comprising multiple pick-up heads 256, and a gap of chamber 258 defined between the central shaft 252 and the rotatable portion 254. With the second exemplary turret structure 250, vacuum is continuously maintained within the chamber 258. The chamber 258 functions as a buffer against changes to vacuum pressure and helps to overcome an unstable applied vacuum found in the first exemplary existing turret structure 200. Vacuum is constantly applied through each pick-up head 256 onto the semiconductor component attached thereto during rotation of the pick-up head 256 about the central shaft 252. Maintenance of a continuous vacuum within the chamber 258 facilitates application of a continuous vacuum through the pick-up head 256 for securing the semiconductor component thereto during rotation. However, the presence of the chamber 258, and therefore vacuum, between the central shaft 252 and the rotatable portion 254 increases difficulty, due to the additional volume of vacuum in the chamber 258, to accurately and quickly adjusting the pressure of air being purged through the pick-up heads 256 for subsequently detaching the semiconductor components from the pick-up heads 256. In addition, air being purged passes through the chamber 258, thereby affecting the vacuum pressure within the chamber 258. Accordingly, maintaining an optimum and constant pressure within the chamber 258 is significantly difficult with the turret structure 250.
U.S. Pat. No. 6,298,547 of Okuda et al. proposes an apparatus for transferring semiconductor components. More specifically, the apparatus of U.S. Pat. No. 6,298,547 utilizes positive and negative air pressures (i.e. blowing and suction or vacuum) for removing and mounting components to pick-up heads or nozzles. Vacuum is applied to hold the components to the pick-up heads during displacement of the pick-up heads. Multiple valves are required for the pick-up heads of the apparatus of U.S. Pat. No. 6,298,547. The use of multiple valves for the multiple pick-up heads increases the complexity of controlling application of vacuum or air through the pick-up heads at any given time. Due to the substantial volume within component 224 of U.S. Pat. No. 6,298,547, it may also be difficult to apply vacuum, or to purge air, quickly through the pick-up heads. Thus, the pick and place process may be slowed significantly. The design of U.S. Pat. No. 6,298,547 is more suitable for theta correction of semiconductor components and is very difficult to implement on rotary semiconductor component transfer systems.
There therefore exist needs for improved apparatuses for transferring semiconductor components, especially apparatuses comprising turret structures, for enhancing accuracy and efficiency of at least one of pick-up of the semiconductor components by the pick-up heads, securing of the semiconductor components to the pick-up heads during rotation or displacement thereof, and subsequent detachment of the semiconductor components from the pick-up heads.